Many companies are actively seeking to create a display element that is easily manufacturable These display elements can be either active, i.e. emit light such as LED, OLED, PLED, EL, or passive, i.e. affect the passage, reflection or refraction of light such as LCD, CLC, e-ink etc.. Some passive systems are bistable such they can be switched and remain switched after the power has been removed. Most configurations previously disclosed can be readily adapted to colour functionality.
Various electrowetting display elements are known in the prior art.
U.S. Pat. No. 6,473,492 discloses a fluid element device that rearranges fluid within a capillary tube. A voltage is used to move the fluid within the capillary to a desired level. U.S. 2002/0080920 discloses a filter device using an array of elements based upon U.S. Pat. No. 6,473,492 for use with X-ray imaging equipment. U.S. 2003/0085850 discloses an electrostatic device that changes a meniscus shape such that the focal length of the device changes.
U.S. Pat. No. 6,449,081 describes a focusing element based on the electrowetting phenomenon. WO2/002099527 describes a display element with a defined prismatic structure that contains two immiscible fluids together with electrodes such that the fluid can be rearranged with the cell.
Problem to be Solved by the Invention
In display elements based on the rearrangement of liquid it is of benefit to ensure the liquid is captured by capillary forces. This is achieved by making the elements small. Thus the existing art does not easily address the requirement for large pixel areas. Furthermore, the existing art describes structures that necessarily require micro-fabrication and thus relatively complex construction methods.
It is the purpose of the current invention to provide a new device based on a combination of mechanisms that has previously not been contemplated. This class of device will be adaptable to colour though the description below is for a single colour element. The display element is capacitative in nature and thus has low power consumption and is switched by low voltages. The element modifies the reflectivity of the surface thereof.